1. Field of the Invention:
This invention relates to an improvement in an image carrier cleaning device for an electrophotographic copying machine, and more particularly, to an improvement in a cleaning device including cleaning means for separating residual magnetic toner or magnetic developer, both hereinafter referred to as toner or magnetic toner, on an image carrier from the image carrier and transfer means for magnetically absorbing the separated magnetic toner and transferring and removing it away.
2. Description of the Prior Art:
As a cleaning device of the kind referred to in the above, several types of cleaning devices have conventionally been suggested.
One of the conventional cleaning devices is the one wherein the transfer means absorbs directly the magnetic toner on the surface of its rotary magnet roller and transfers and removes the toner away by the rotation of the magnetic roller; or the transfer means absorbs the magnetic toner on the surface of a rotary or stationary sleeve covering the rotary magnet roller or rotary magnet member of the transfer means and transfers and removes the toner away by the rotation of roller or magnet.
This type of conventional cleaning device is, however, defective in some respects. This cleaning device employs the direct absorbing system of magnetic toner on the rotary magnet roller or sleeve of the transfer means, and therefore, it requires a toner scraping means additionally for removing the toner attached directly to the transfer means. Further, the absorbed toner is likely to accumulate around the part where the toner scraping means is provided, and a filming of toner is apt to occur on the rotary magnet roller or sleeve, both resulting in a degradation of performance of transferring and removing the magnetic toner.
The scraping operation of the toner scraping means causes a rapid wearing of the surface of the rotary magnet roller or sleeve and the toner scraping means itself. In addition, it is also one of the greatest problems to be overcome that the toner scraping means unfavorably gives resistance to the drive of the rotary magnet roller and the like.
Another conventional cleaning device is the one wherein the transfer means is very simple in structure without a provision of any kind of toner scraping means, but employs the magnetic force for removing the toner away. In more detail, the transfer means is constituted by a rotary magnet member and a guide member of the surface of which a shifting field is induced by the rotary magnet member and which covers the surface of the rotary magnet member at least from the part where the rotary magnet member approaches the image carrier to the part on the opposite side where the magnetic toner drops off by its own gravity. This cleaning device also includes a cleaning means for separating the toner from the image carrier. In operation, the magnetic toner remaining on the image carrier is separated by the cleaning means, caught by the shifting field on the surface of the guide member and transferred to the opposite side, where it comes out of the influence of the magnetic force of the rotary magnet member and drops down by its own gravity.
This second conventional cleaning device is advantageous over the first one in that no additional toner scraping means is needed for scraping toner. However, the second device has also several defects which are expected to remove. One of the defects is that the transferred toner is apt to stay on the surface of the guide member at the part where the influence of the magnetic force of the rotary magnet member is relatively weak. Another defect is that the dropping toner accumulates at one position, not utilizing effectively a reservoir for retaining the collected toner.